Static mixer for mixing urea aqueous solution and engine exhaust gas

ABSTRACT

The present disclosure relates to a static mixer for mixing a urea solution and engine exhaust gas. The static mixer includes: an external tube including one end portion connected to an exhaust manifold of a diesel engine, the other end portion connected to an SCR (Selective Catalytic Reduction), and a part with which a urea solution injection adaptor is provided; an internal tube installed inside the external tube so as to have a constant gap between at least a part of an outer wall surface and an inner wall surface of the external tube; and a channel unit comprising a plurality of guiding channels provided inside the internal tube in a longitudinal direction, and having an inlet portion facing a lower end portion of the urea solution injector adaptor. The present disclosure may make the exhaust gas and the urea solution before passing through the SCR pass through the inlet portion and the plurality of guiding channels of the channel unit to form fine and even mixed gas, thereby largely decreasing an amount of nitride oxide (NOx) discharged to the air by improving a catalytic reduction reaction ratio in the SCR.

This Application is a Section 371 National Stage Application ofInternational Application No. PCT/KR2011/004979, filed Jul. 7, 2011 andpublished, not in English, as WO2012/005527 on Jan. 12, 2012.

FIELD OF THE DISCLOSURE

The present disclosure relates to a static mixer for mixing a ureasolution and engine exhaust gas, and more particularly, to a staticmixer for mixing a urea solution and engine exhaust gas capable offinely and evenly mixing exhaust gas discharged from an exhaust manifoldof a diesel engine to an inlet portion of an SCR (Selective CatalyticReduction) of an exhaust pipe and a urea solution supplied from a ureasolution injector of the exhaust pipe to the inlet portion of the SCR inorder to decrease an amount of exhaust gas generated during a combustionprocess of mixed gas of the diesel engine and accompanying nitrogenoxide (NOx) discharged to the atmosphere.

BACKGROUND OF THE DISCLOSURE

In general, a diesel engine injects fuel, such as diesel, into acombustion chamber in a state where air supplied from the outside to thecombustion chamber is compressed at a high temperature and highpressure, to generate output by turning force of a crank shaft connectedwith a connecting rod of a vertically moving piston by explosive forcegenerated during a process of combusting and exploding mixed gas of airand fuel.

In general, in the diesel engine, fuel efficiency is considerablychanged according to a mixture ratio (for example, an air-fuel ratio) ofthe air and the fuel supplied to the combustion chamber. When the amountof air supplied to the combustion chamber is larger than that of thefuel supplied to the combustion chamber, output is greatly increased,but the air supplied to the combustion chamber the air and is harmful tothe human body, and an amount of generation of nitrogen oxide (NOx)which is the cause of acid rain, photochemical smog phenomenon, and thelike is increased. Contrary to this, when the amount of air supplied tothe combustion chamber is smaller than that of the fuel supplied to thecombustion chamber, output deteriorates and a PM (particulate matter) orsoot is increased.

Because of the aforementioned combustion characteristic of the dieselengine, a recent diesel engine has employed an exhaust gaspost-treatment method of increasing the amount of air supplied to thecombustion chamber to be larger than of the fuel supplied to thecombustion chamber to considerably increase output, and making mixed gasof a urea solution and exhaust gas pass through an SCR by injecting theurea solution to the inlet portion of the SCR to change nitrogen oxide(NOx) accompanied by the exhaust gas to innoxious water (H₂O) andnitrogen (N₂).

In general, a mixer of the diesel engine serving to mix a urea solutionand exhaust gas for the exhaust gas post-treatment includes an exhaustpipe including a urea solution injector adapter in which a urea solutioninjector is simply mounted, and a channel unit installed inside theexhaust pipe and including a plurality of guiding channels.

Accordingly, when the diesel engine is operated, exhaust gas generatedin a combustion chamber and the urea solution injected from the ureasolution injector are mixed together while passing through the pluralityof guiding channels of the channel unit, to be guided to an SCR disposedat a rear side of the mixer, and the nitrogen oxide (NOx) accompanied bythe exhaust gas generates catalytic reduction reaction with the ureasolution while passing through the SCR to be changed to innoxious waterand nitrogen.

However, since the mixer of the diesel engine in the related art has astructure in which the channel unit including the plurality of guidingchannels is simply accommodated inside the exhaust pipe, there is aproblem in that the exhaust gas discharged from an exhaust manifold ofthe engine to the mixer is not finely and evenly mixed well with theurea solution supplied from the urea solution injector, so that anamount of nitrogen oxide (NOx) discharged to the atmosphere is notlargely decreased.

Further, in the mixer of the diesel engine in the related art, since theexhaust pipe accommodating the channel unit has a form of a single duct,when the urea solution is in direct contact with an inner wall surfaceof the exhaust pipe directly exposed to the air, the urea solution isnot evaporated and flows down along the inner wall surface of theexhaust pipe, so that there is a problem in that the urea solution isnot appropriately used for decreasing nitrogen oxide (NOx) and isdirectly discharged to the outside.

The discussion above is merely provided for general backgroundinformation and is not intended to be used as an aid in determining thescope of the claimed subject matter.

SUMMARY

This summary and the abstract are provided to introduce a selection ofconcepts in a simplified form that are further described below in theDetailed Description. The summary and the abstract are not intended toidentify key features or essential features of the claimed subjectmatter, nor are they intended to be used as an aid in determining thescope of the claimed subject matter.

Accordingly, the present disclosure provides a static mixer for mixing aurea solution and engine exhaust gas, by which exhaust gas beforepassing through an SCR and the urea solution can be finely and evenlymixed in order to considerably decrease an amount of nitrogen oxide(NOx) discharged to the atmosphere.

Further, the present disclosure provides a static mixer for mixing aurea solution and engine exhaust gas, by which exhaust gas and a ureasolution can be finely and evenly mixed by improving an evaporationenvironment of the urea solution supplied from a urea solution injectorto an input portion of an SCR, thereby decreasing an amount of nitrogenoxide (NOx) discharged to the atmosphere and removing waste of the ureasolution.

In order to achieve the above object, the present disclosure provides astatic mixer for mixing a urea solution and engine exhaust gas,including: an external tube including one end portion connected to anexhaust manifold of a diesel engine, the other end portion connected toan SCR (Selective Catalytic Reduction), and a part with which a ureasolution injection adaptor is provided; an internal tube installedinside the external tube so as to have a constant gap between at least apart of an outer wall surface and an inner wall surface of the externaltube; and a channel unit including a plurality of guiding channelsprovided inside the internal tube in a longitudinal direction, andhaving a inlet portion facing a lower end portion of the urea solutioninjector adaptor.

Further, the present disclosure further provides detailed exemplaryembodiments for the exemplary embodiment of the present disclosurebelow.

According to the exemplary embodiment of the present disclosure, theinternal tube may include at least one protrusion at an outer peripheralportion.

According to the exemplary embodiment of the present disclosure, thechannel unit may include a plurality of first channel plates arranged inthe internal tube with predetermined intervals therebetween, and aplurality of second channel plates inclined at a predetermined anglewith respect to the plurality of first plates and disposed to cross theplurality of first plates with predetermined intervals therebetween.

According to the exemplary embodiment of the present disclosure, anexposed portion of at least one of the plurality of first and secondchannel plates may have at least one through hole so as to achieve afine and even mixing behavior between the exhaust gas and the ureasolution.

According to the exemplary embodiment of the present disclosure, aplurality of blades may be provided at an end portion of an outlet sideof at least one of the plurality of first and second channel plates soas to achieve a fine and even mixing behavior between the exhaust gasand the urea solution.

According to the exemplary embodiment of the present disclosure, theplurality of blades may be inclinedly arranged in an opposite directionfor each layer of the first and second channel plates.

According to the exemplary embodiment of the present disclosure, theinlet portion of the channel unit may include a first inclined portionhaving a predetermined angle with respect to a longitudinal direction ofthe internal tube, and a second inclined portion having a predeterminedangle with respect to the first inclined portion.

According to the exemplary embodiment of the present disclosure, anorientation angle of the first inclined portion may be 0 to 30° in anoutside direction with respect to a virtual axial line perpendicular tothe longitudinal direction of the internal tube.

According to the exemplary embodiment of the present disclosure, each ofend surfaces of the first and second inclined portions at an end surfaceof an inlet side may have a shape of a straight line, a curved line, ora combination thereof.

According to the exemplary embodiment of the present disclosure, therespective three first and second channel plates are included so as toform four rooms in one direction and the other direction, respectively.

According to the exemplary embodiment of the present disclosure, the gapbetween the internal tube and the external tube is 5 to 10 mm.

According to the present disclosure, the present disclosure may formfine and even mixed gas by providing the channel unit having theplurality of guiding channels and the inlet portion inside the internaltube shaped like a dual tube including the external tube surrounding theinternal tube at a predetermined gap, and making the exhaust gas and theurea solution before passing through the SCR pass through the inletportion and the plurality of guiding channels of the channel unit,thereby largely decreasing an amount of nitride oxide (NOx) dischargedto the outside by improving a catalytic reduction reaction ratio in theSCR.

Further, the present disclosure provides the channel unit including theplurality of guiding channels and the inlet portion inside the internaltube shaped like a dual tube to insulate the internal tube against theexternal tube directly exposed to the outside, so that an evaporationratio of the urea solution supplied from the urea solution injector tothe inlet portion and the plurality of guiding channels of the channelunit, thereby decreasing an amount of nitride oxide (NOx) discharged tothe outside and removing waste of the urea solution.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view illustrating a static mixer formixing a urea solution and engine exhaust gas according to the presentdisclosure.

FIG. 2 is a schematic perspective view illustrating an end portion of anoutlet of the static mixer according to the present disclosure.

FIG. 3 is a schematic perspective view illustrating an internal tube anda channel unit provided inside the internal tube of the static mixeraccording to the present disclosure.

FIG. 4 is a schematic cross-sectional view illustrating an angleorientation relation between a first inclined portion of a inlet portionprovided at the channel unit and an external tube of the static mixeraccording to the present disclosure.

Description of Main Reference Numerals of Drawings 1: Static mixer 102:External tube 3: Internal tube 3a: Protrusion 5: Urea solution injectoradaptor 10: Channel unit 11: Guiding channel 12: Bent inlet portion 12a:First inclined portion 12b: Second inclined portion 13: First channelplate 14: Second channel plate 15: Through-hole 16: Blade

DETAILED DESCRIPTION

Hereinafter, an exemplary embodiment of a static mixer for mixing a ureasolution and engine exhaust gas according to the present disclosure willbe described with reference to FIGS. 1 to 4.

First, a term “static mixer” is an expression widely used in acorresponding business field and is a counterpart concept to a dynamicmixer, and means a mixer (or a mixing device) for finely and evenlymixing exhaust gas and a urea solution without a dynamic motion.

Further, in a description of the present disclosure, two terms of “aplurality of” and “multiple” are discriminatingly used. The term of “aplurality of” is used so as to emphasize a case in which a technicalmeaning is significant when the number of corresponding constituentelements is two or more, and the term of “multiple” is used so as torepresent a case in which there are simply a lot of correspondingconstituent elements.

The static mixer 1 of the present disclosure includes, as illustrated inFIGS. 1 to 3, an external tube 2, an internal tube 3, and a channel unit10. Here, one end portion of the external tube 2 is connected to anexhaust manifold (not illustrated) of a diesel engine, and the other endportion is connected to an SCR (not illustrated), and a urea solutioninjector adaptor 5 is provided at a part of the external tube 2. Theexternal tube 2 may be connected to an exhaust pipe (not illustrated) bya welding method or a detachable method.

The internal tube 3 is fixed while being accommodated inside theexternal tube 2 so that at least one portion of an outer wall surface ofthe internal tube 3 has a constant gap from an inner wall surface of theexternal tube 2.

The channel unit 10 is provided inside the internal tube 3 and includesmultiple guiding channels 11 in a longitudinal direction, and has ainlet portion 12 facing a lower end portion of the urea solutioninjector adaptor 5.

According to the static mixer 1 of the present disclosure, exhaust gasdischarged from the exhaust manifold to the static mixer 1 of the dieselengine and the urea solution supplied from a urea solution injector (notillustrated) installed in the urea solution injector adaptor 5 of thestatic mixer 1 to the static mixer 1 are finely and evenly mixed witheach other while passing through the channel unit 10 including the bentinlet portion 12 and the multiple guiding channels 11.

Further, according to the static mixer 1 of the present disclosure, theurea solution supplied from the urea solution injector (not illustrated)installed in the urea solution injector adaptor 5 to the static mixer 1may be injected to the channel unit 10 inside the internal tube 3,thereby solving a problem of the related art in that the urea solutionis in directly contact with the inner wall surface of the external tube2 to be changed in a liquid state and flow down along the inner wallsurface of the external tube 2.

Accordingly, the static mixer 1 of the present disclosure enables mixedgas of the exhaust gas and the urea solution finely and evenly mixedwell while passing through the static mixer to well have a catalyticreduction reaction when passing through the SCR (not illustrated),thereby eventually greatly decreasing an amount of nitrogen oxide (NOx)discharged to the air and decreasing waste of the urea solution.

Further, the static mixer for mixing the urea solution and the engineexhaust gas according to the present disclosure may be implemented as aform further defined by detailed exemplary embodiments below in additionto the aforementioned fundamental configuration.

As an exemplary embodiment, the internal tube 3 may be provided in aform having at least one or more protrusions 3 a at an outer peripheralportion so as to maintain a constant gap from the external tube 2. Theprotrusion 3 a may be formed at one point, two points, three points, ormore points than three points in the external surface of the internaltube 3 while having a predetermined interval therebetween. The gapbetween the internal tube 3 and the external tube 2 may be convenientlyformed by a structure of the protrusion of the internal tube. The gapbetween the internal tube 3 and the external tube 2 may be formed byinterposing a separate insulating spacer (not illustrated).

As the exemplary embodiment, the channel unit 10 may include a pluralityof first channel plates 13 arranged in the internal tube 3 withpredetermined intervals therebetween, and a plurality of second channelplates 14 inclined with respect to the plurality of first plates 13 at apredetermined angle, and disposed to cross the plurality of first plates13 with predetermined intervals therebetween. The plurality of guidingchannels 11 for guiding the exhaust gas, the urea solution, or mixed gasin which the exhaust gas is mixed with the urea solution may beconveniently formed by a structure of the plurality of first and secondchannel plates.

As the exemplary embodiment, an exposed portion of at least one of theplurality of first and second channel plates 13 and 14 may be providedin a form having at least one through-hole 15 so that the exhaust gasand the urea solution are evenly mixed. In this case, the through hole15 may have various shapes, such as a circular shape, an ellipticalshape, a slit, or a slot. A structure of the through-hole of theplurality of first and second channel plates improves an active mixingbehavior between the exhaust gas and the urea solution guided to theadjacent guiding channels among the plurality of guiding channels 11.

As the exemplary embodiment, a plurality of blades 16 may be provided atan end portion of an outlet side of at least one of the plurality offirst and second channel plates 13 and 14 so that the exhaust gas andthe urea solution are finely and evenly mixed. In this case, theplurality of blades 16 may be inclinedly arranged in an oppositedirection for each layer of the first and second channel plates 13 and14. This is because an active mixing behavior between the exhaust gasand the urea solution is improved by creating a vortex phenomenon in theexhaust gas and the urea solution passing through the end portions ofthe outlet sides of the plurality of first and second channels plates 13and 14.

As the exemplary embodiment, the internal tube 3 may be fixedconcentrically or eccentrically with respect to the external tube 2. Inthis case, a structure in which the internal tube 3 is disposedconcentrically with respect to the external tube 2 has an advantage inthat the gap between the internal tube 3 and the external tube 2 may beregularly formed. A structure in which the internal tube 3 is disposedeccentrically with respect to the external tube 2 has an advantage inthat the internal tube 3 may be simply and conveniently fixed to theexternal tube 2.

Otherwise, the gap between the internal tube 3 and the external tube 2may be 5 to 10 mm. This is because there is a disadvantage in that aninsulation effect of the internal tube 3 against the external tube 2 isdecreased when the gap between the internal tube 3 and the external tube2 is less than 5 mm, and there are high concerns regarding the directdischarge of a part of the exhaust toward the SCR without the mixingbehavior with the urea solution when the gap between the internal tube 3and the external tube 2 exceeds 10 nm.

As the exemplary embodiment, the bent inlet portion 12 of the channelunit 10 may include a first inclined portion 12 a having a predeterminedangle with respect to a longitudinal direction of the internal tube 3,and a second inclined portion 12 b having a predetermined angle withrespect to the first inclined portion 12 a. In this case, as illustratedin FIG. 4, an orientation angle of the first inclined portion 12 a maybe 0 to 30° in an outside direction with respect to a virtual axial lineperpendicular to the longitudinal direction of the internal tube 3. Thisis because there is a disadvantage in that when the orientation angle ofthe first inclined portion 12 a is smaller than 0° (that is, the firstinclined portion 12 a is inwardly formed with respect to the verticalaxial line of the internal tube), or exceeds 30°, the mixture ratio ofthe exhaust gas to the urea solution is remarkably decreased compared toa case where the orientation angle of the first inclined portion 12 ahas the aforementioned range. Otherwise, end surfaces of the first andsecond inclined portions 12 a and 12 b at the inlet side may be formedin a shape of a straight line, a curved line, or a combination thereof.

As the exemplary embodiment, the three first channel plates 13 and thethree second channel plates 14 may be included so as to have four roomsin one direction and the other direction, respectively. The structure ofthe plurality of first and second channel plates having theaforementioned arrangement improves the mixing behavior between theexhaust gas and the urea solution compared to a case where the number ofeach of the first and second channels plates is smaller than 3 orexceeds 3. This is because discharge pressure of the exhaust gas and/ormixing power between the exhaust gas and the urea solution is changedaccording to a dense arrangement or sparse arrangement of the pluralityof first and second channel plates 13 and 14.

An operation of the static mixer for mixing the urea solution and theexhaust gas configured as described above will be described withreference to FIGS. 1 to 4 below.

When the static mixer 1 according to the present disclosure is installedat the inlet side of the SCR so as to form a partial portion of theexhaust pipe connecting the exhaust manifold (not illustrated) and theSCR (not illustrated) of the diesel engine and a diesel engine isoperated, exhaust gas generated at the time of combustion and explosionin the combustion chamber of the diesel engine during the operation ofthe diesel engine is discharged toward the inlet portion of the channelunit 10 of the static mixer 1 through the exhaust manifold.

Further, a urea solution is simultaneously injected from the ureasolution injector (not illustrated) installed in the urea solutioninjector adaptor 5 of the external tube 2 of the static mixer 1 to theinlet portion of the channel unit 10 of the static mixer 1.

In this case, the exhaust gas and the urea solution are primarily finelyand evenly mixed together while flowing inside the plurality of guidingchannels 11 through the bent inlet portion 12 of the channel unit 10. Inthe meantime, in a case of the exemplary embodiment in which thethrough-hole 15 is further provided at the exposed portions of the firstand second channel plates 13 and 14 of the channel unit 10, the mixingbehavior between the exhaust gas and the urea solution passing throughthe plurality of guiding channels 11 may be more actively performed.

Subsequently, the exhaust gas and the urea solution discharged to theend portion of the outlet side of the channel unit 10 through theplurality of guiding channels 11 of the channel unit 10 generate avortex while crashing against the plurality of blades 16 of the channelunit 10, thereby being more finely and evenly mixed secondarily.

Mixed gas of the exhaust gas and the urea solution, which become fineand even in an optimum state while passing through the channel unit 10of the static mixer 1 according to the present disclosure, is guided tothe SCR. Then, the nitrogen oxide (NOx) accompanied by the exhaust gasincurs a catalytic reduction reaction with the urea solution whilepassing through the SCR to be changed to innoxious water (H2O) andnitrogen (N2) and discharged to the air.

The aforementioned present disclosure is not limited to theaforementioned exemplary embodiments and the accompanying drawings, andsimple substitution, change, and modification within the technicalspirit of the present disclosure are obvious to those skilled in theart.

The static mixer for mixing a urea solution and engine exhaust gasaccording to the present disclosure is installed at a side of an exhaustpipe of a diesel engine to change nitrogen oxide (NOx) accompanied bythe exhaust gas into innoxious water (H2O) and nitrogen (N2), so thatthe static mixer is usable for decreasing atmosphere environmentalpollution.

Although the present disclosure has been described with reference toexemplary and preferred embodiments, workers skilled in the art willrecognize that changes may be made in form and detail without departingfrom the spirit and scope of the disclosure.

1-11. (canceled)
 12. A static mixer for mixing a urea solution andengine exhaust gas, comprising: an external tube including one endportion connected to an exhaust manifold of a diesel engine, the otherend portion connected to an SCR (Selective Catalytic Reduction), and apart with which a urea solution injection adaptor is provided; and achannel unit provided inside the external tube, comprising a pluralityof guiding channels in a longitudinal direction, and having an inletportion facing a lower end portion of the urea solution injectoradaptor.
 13. The static mixer for mixing a urea solution and engineexhaust gas of claim 12, further comprising: an internal tube installedinside the external tube so as to have a constant gap between at least apart of an outer wall surface and an inner wall surface of the externaltube, wherein the inlet portion is installed inside the internal tube.14. The static mixer of claim 13, wherein the internal tube includes atleast one protrusion at an outer peripheral portion.
 15. The staticmixer of claim 13, wherein the channel unit comprises a plurality offirst channel plates arranged in the internal tube with predeterminedintervals therebetween, and a plurality of second channel platesinclined at a predetermined angle with respect to the plurality of firstplates and disposed to cross the plurality of first plates withpredetermined intervals therebetween.
 16. The static mixer of claim 15,wherein an exposed portion of at least one of the plurality of first andsecond channel plates has at least one through hole so as to achieve afine and even mixing behavior between the exhaust gas and the ureasolution.
 17. The static mixer of claim 15, wherein a plurality ofblades is provided at an end portion of an outlet side of at least oneof the plurality of first and second channel plates so as to achieve afine and even mixing behavior between the exhaust gas and the ureasolution.
 18. The static mixer of claim 17, wherein the plurality ofblades is inclinedly arranged in an opposite direction for each layer ofthe first and second channel plates.
 19. The static mixer of claim 13,wherein the inlet portion of the channel unit includes a first inclinedportion having a predetermined angle with respect to a longitudinaldirection of the internal tube, and a second inclined portion having apredetermined angle with respect to the first inclined portion.
 20. Thestatic mixer of claim 19, wherein an orientation angle of the firstinclined portion is 0 to 30° in an outside direction with respect to avirtual axial line perpendicular to the longitudinal direction of theinternal tube.
 21. The static mixer of claim 19, wherein each of endsurfaces of the first and second inclined portions at an end surface ofan inlet side has a shape of a straight line, a curved line, or acombination thereof.
 22. The static mixer of claim 15, wherein therespective three first and second channel plates are included so as toform four rooms in one direction and the other direction, respectively.23. The static mixer of claim 13, wherein the gap between the internaltube and the external tube is 5 to 10 mm.